The Pegi rating of the Manhunt is 18, because it contains extreme violence. Hence, it is not meant to be played by 12-15 year old children. Why it has been judged to use this game and 12-15 year old children necessary?

A publication by Ivarsson et al. (2008), “Playing a violent television game affects heart rate variability” (in Acta Pædiatrica) assumes that the games are comparable, because they did not find differences between the games with an Actiwatch in motor-patternsof playing.Yet, they failed to account the qualitative differences between games, as Annika Waern point out on her blog. (I assume that it is a part of the research promoted in the above-mentioned su.se page as the measurements, games, and main authors are the same that are mentioned on valdsamma-dataspel-paverkar-kroppen-1.79509)

The study does not do anything to control the qualitative factors. It is possible that the better or just more intensive game have more lasting impact despite the content, isn’t it?

Waern continues:

[T]heir second study is more interesting than their first. Remember that the second study showed that the boys who played little games reacted stronger to Manhunt than those who played a lot of games. Ivarsson interprets this as a desensitization towards violence (in general), but there are at least two other possible explanations. One is that the boys who played a lot of games understood the horror genre better, thereby getting less scared. But the other explanation, and the one I think is the right one, is that they were better at understanding the game as a game.

These are possible alternative explanations to desensitization. In addition, just be able to prepare oneself for the future events help.

Ivarsson is rather explicit on her presupposition:

Malena Ivarsson am personally convinced that violence in computer games in the long run affects the players, and the subtle but gradually can contribute to changing behaviors. (cited in Lundström, translation by google)

I have iterated before why I think that the above premise about a simple causal connection where violent videogames are claimed to cause violent behavior is not plausible.

In the end, based on Ivarsson et al (2008) we can conclude that these two game players had different heart rate patterns and possibility some sleeping issues. So, the authors show evidence to support their premise (in this specific case). But what that means in general and how, for example, this study supports claims on valdsamma-dataspel-paverkar-kroppen-1.79509 or what Waern summarizes on her blog?